1. Field of the Invention
The present invention relates to a scanning device with a resonant light deflector for recording data on and reading data from a scanned medium highly accurately by controlling the speed at which the scanned medium is fed in an auxiliary scanning direction depending on a frequency variation caused as by a change in the temperature of the resonant light deflector.
2. Description of the Related Art
Laser beam printers for recording an image or the like by deflecting a laser beam at high speed on a scanned medium such as a photographic film are used in various applications. The laser beam may be deflected at high speed by a resonant light deflector which comprises a reflecting mirror supported by a resilient member and oscillatable at its natural frequency.
Because the natural frequency of the resilient member varies with temperature, the resonant light deflector has a resonant frequency as shown in FIG. 2 of the accompanying drawings. The temperature of the resonant light deflector varies with an ambient temperature and due to the heat produced thereby. The resonant frequency of the resonant light deflector cannot be adjusted since it is based on the natural frequency of the resilient member.
There is known a scanning device in which an image is recorded on a scanned medium such as a photographic film using such a resonant light deflector. If a scanned medium is fed in an auxiliary scanning direction at a constant speed in such a scanning device, the scanning pitch in the auxiliary scanning direction is varied by a change in the frequency of the resonant light deflector, resulting in irregularities in the recorded image. To alleviate such a drawback, it has been proposed to oscillate the resonant light deflector for a certain period of time without recording any image after the scanning device has been started, or to preheat the resonant light deflector until it is kept at a constant temperature for thereby stabilizing the resonant frequency.
However, these proposals make the scanning device inefficient since no recording process can be carried out until the resonant frequency is stabilized. In addition, the attempts fail to avoid irregularities which are produced in the recorded image due to temperature changes while the scanning device is in recording operation.